EQUILIBRIUM REACTIONS BETWEEN MOLECULAR AND IONIC SPECIES IN PURE MOLTEN LICL AND IN LICL+MCL (M=NA, K, RB) MELTS INVESTIGATED BY COMPUTATIONAL CHEMISTRY

In order to study the microscopic structures of molten lithium chlorid e and selected binary chloride melts containing lithium chloride, DFT calculations were performed with DMOL software at the DNP/UHF/BLYP lev el to study all the possible (stable) isolated chloride complexes of a lkaline metals. Results on geometry, energy, vibrational spectrum and Mulliken population are summarized. In addition, thermostatistical cal culations were carried out to obtain the thermodynamic data relative t o equilibrium reactions occuring in melts. It was demonstrated that th e general equilibrium LiCl + 2MCl reversible arrow LiCL(2)(-) + M(2)Cl (+) predominates and the temperature and composition dependence of the percentage of LiCl2- for a given melt (molten LiCl-NaCl, LiCl-KCl and LiCl-RbCl) was determined. This study emphasizes the role of the coun ter cation on the structure of molten alkali metal chlorides.